Roller type hemming apparatus

ABSTRACT

A roller type hemming apparatus includes a support member having a slide bore. A compressible fluid shock absorber is disposed in the support member and is extendable into the slide bore. A guided slide member is received in the slide bore and the slide member contacts the shock absorber. The slide member includes a flange disposed outside of the slide bore. The apparatus further includes a hem roller. The hem roller is rotatably mounted on the slide member flange. A retaining plate having an opening therein is mounted to the support member adjacent the slide bore for retaining a portion of the slide member in the slide bore and for limiting travel of the slide member out of the slide bore. The movement of the slide member is tempered during the application of an abrupt compressive force.

TECHNICAL FIELD

This invention relates to a roller type hemming apparatus for edge hemming vehicle closure panels such as hemming of door panels, hood panels, and decklid panels.

BACKGROUND OF THE INVENTION

It is known in the vehicle closure panel hemming art that roller hemmers can be used to hem the edges of metal, for example aluminum, automotive parts such as door panels, hood panels, and decklid panels.

Conventionally, roller hemming apparatus may be mounted to a multi-axis controllable robot and may include a hem roller carried by a support. The conventional hemming apparatus is adapted for hemming a bent portion of a workpiece, such as a door panel, positioned on a hemming die, by rotating the hem roller under pressure along the bent portion. The conventional roller type hemming apparatus can thus be used for continuous hemming along the contour of the edge of the workpiece.

In order to achieve good hemming with such a conventional roller hemming apparatus, however, the robot must move the hem roller along the edge of the workpiece at a constant distance from the hemming die. The robot is not composed of a perfectly rigid body, and when the hem roller is positioned against the edge of the workpiece, the robot arm or the hem roller may be deflected by its own resiliency or by a repulsive force exerted by the edge of the workpiece itself. For example, the edge of the workpiece may have inconsistent material dimensions such as bumps that exert a repulsive force on the robot. This results in interruption of the pressing force applied by the hem roller and therefore imperfect hemming of the workpiece. Springs have been disposed in the hemming roller support to compensate for the interrupted pressing force, but alone springs have proven inefficient and unpredictable.

Temperature variations in the environment surrounding the roller hemming robot may also undesirably affect the accuracy of the hemming performed by the robot.

Further, the edge of a workpiece to be hemmed may have a complex configuration. This makes it difficult for a conventional hemming apparatus to achieve adequate hemming of the workpiece.

SUMMARY OF THE INVENTION

The present invention provides a roller type hemming apparatus which includes a hem roller that can accurately follow the configuration of a bent portion of a workpiece to be hemmed and more accurately and uninterruptably apply a consistent hemming force.

The present invention also provides a roller type hemming apparatus wherein deflection of the hem roller is limited while the hemming force is maintained by a compressible fluid shock absorber. The hem roller is loaded against the workpiece at a predetermined pressure, and when the pressure on the hem roller exceeds the predetermined pressure, the shock absorber absorbs the excess pressure.

More particularly, a roller type hemming apparatus in accordance with the present invention includes a support member having a slide bore. A compressible fluid shock absorber, such as a nitrogen gas shock absorber or similar, is disposed in the support member and is extendable into the slide bore. A guided slide member is received in the slide bore and the slide member contacts the shock absorber. The slide member includes a flange disposed outside of the slide bore. The apparatus further includes a hem roller. The hem roller is rotatably mounted on the slide member flange. A retaining plate having an opening therein is mounted to the support member adjacent the slide bore for retaining a portion of the slide member in the slide bore and for limiting travel of the slide member out of the slide bore. The movement of the slide member is tempered during the application of an abrupt compressive force.

In a specific embodiment, the roller type hemming apparatus may further include a radially disposed bearing arrangement inserted into the slide bore for guiding the slide member in the slide bore. Anti-rotate guide members adjacent the retaining plate may limit rotation of the slide member in the slide bore. The slide member may contact a surface of the anti-rotate guide members. The slide member may have curved sides intermediate a pair of opposed flat surfaces, and the flat surface of the guide members may contact the flat surfaces of the slide member. The slide member may also have steps such that the portion of the slide member retained in the slide bore is larger in width than the opening in the retaining plate while the remainder of the slide member is smaller in width than the opening.

The retaining plate may be adjustable to selectively delimit a range of deflection of the slide member, thereby compressing and decompressing the shock absorber to establish a preload force. The retaining plate may be adjustable by varying the distance between the retaining plate and the support member. The apparatus may be adapted for operable connection to a work arm of a multi-axis robot and the apparatus may be fastened to a forward end of a hand of the robot.

With the above construction, as the hem roller is displaceable in a direction corresponding to the pressing direction of the robot hand, deflection of the robot hand or any difference between the traveling path of the robot hand and the peripheral contour of the workpiece can be absorbed, permitting the hem roller to accurately follow the bent portion of the workpiece. The hemming apparatus also allows the hem roller to achieve a higher quality hem in difficult areas such as around corners and charter lines in the workpiece.

These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an environmental view of a roller type hemming apparatus in accordance with the present invention illustrating hemming a workpiece with the aid of a robot hand;

FIG. 2 is a cutaway side view of a roller type hemming apparatus in accordance with the present invention;

FIG. 3 is a cutaway side view of the roller type hemming apparatus of FIG. 2 rotated 90 degrees;

FIG. 4 is a cross-sectional view of the slide member of the roller type hemming apparatus taken along the line 4-4 in FIG. 2;

FIG. 5 is a partial view of an alternative embodiment of a roller type hemming apparatus in accordance with the present invention; and

FIG. 6 is a cross-sectional view of a slide member of the roller type hemming apparatus taken along the line 6-6 in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail and to FIG. 1 in particular, a roller type hemming apparatus 10 in accordance with the present invention is adapted for operable connection to a work arm, such as a multi-axis controllable robot hand 12 to which a predetermined traveling path may be preliminarily taught. The roller type hemming apparatus 10 includes a hem roller support 14 mounted on the forward end of the robot hand 12, and a hem roller 16 displaceably supported by the hem roller support 14 to be pressed against a workpiece W.

The workpiece W is, for example, a door panel composed of an outer panel Wo and an inner panel Wi. The outer panel Wo has a peripheral portion preliminarily bent upwardly substantially at right angles, and the inner panel Wi has a peripheral stepped portion extending outwardly (see for example FIG. 1). The outer panel Wo and the inner panel Wi may be placed on a lower die 18 with the stepped portion of the inner panel Wi arranged along the inside of the bent portion of the outer panel Wo. The lower die 18 has an upper surface constituting a forming surface 20. The base of the multi-axis controllable robot (not shown) is placed at a predetermined distance away from the lower die 18. The workpiece W is placed on the forming surface 20 of the lower die 18 and may be secured thereto by fixtures (not shown).

As the robot hand 12 is well known in the art, its description will be omitted, and the roller type hemming apparatus 10 will be described in detail.

As shown in FIGS. 2-4, a roller type hemming apparatus 10 in accordance with the present invention includes a support member 24 having a slide bore 26. A compressible fluid shock absorber 28, such as a nitrogen gas shock absorber or similar, is disposed in the support member 24 and is extendable into the slide bore 26. A guided slide member 30 is received in the slide bore 26 and the slide member 30 contacts the shock absorber 28. The slide member 30 includes a flange 32 extending outside of the slide bore 26. The apparatus 10 further includes a hem roller 16. The hem roller 16 is rotatably mounted on the slide member flange 32. A retaining plate 34 having an opening 36 therein is mounted to the support member 24 adjacent the slide bore 26 for retaining a portion 38 of the slide member 30 in the slide bore 26 and for limiting travel of the slide member out of the slide bore. The flange 32 of the slide member 30 extends through the opening 36 in the retaining plate 34. The movement of the slide member 30 is tempered during the application of an abrupt compressive force.

In a specific embodiment, the roller type hemming apparatus 10 may further include a radially disposed bearing arrangement 50 inserted into the slide bore 26 for guiding the slide member 30 in the slide bore. The retaining plate 34 may be adjustable to selectively delimit a range of deflection of the slide member 30, thereby compressing and decompressing the shock absorber 28 to establish a preload force. The retaining plate 34 may be adjustable by varying the distance between the retaining plate and the support member 24. For example, the distance between the retaining plate 34 and the support member 24 may be adjusted by using shims between the support member and the retaining plate. The larger the distance between the retaining plate 34 and the support member 24, the less the shock absorber 28 is compressed by the slide member 30 and hence, the less the preload force that is applied to the shock absorber. The apparatus 10 may be adapted for operable connection to a work arm of a multi-axis robot by way of, for example, a mounting flange 52. The apparatus 10 may be fastened to a forward end of a robot hand 12.

As shown in FIGS. 5-6, in an alternative embodiment, anti-rotate guide members 140 may be disposed adjacent the retaining plate 134 for limiting rotation of the slide member 130 in the slide bore 126. The slide member 130 may contact a surface 142 of the anti-rotate guide members 140 (see, for example, FIG. 5). The slide member 130 may have curved sides 144 intermediate a pair of opposed flat surfaces 146, and the flat surfaces 142 of the guide members 140 may contact the flat surfaces 146 of the slide member 130. The contact between the flat surfaces 146 of the slide member 130 and the flat surfaces 142 of the anti-rotate guide members 140 prevent the slide member from being capable of rotating inside of the slide bore 126 and thereby guide the slide member in a straight path. The slide member 130 may have steps 148 such that the portion 138 of the slide member 130 retained in the slide bore 126 is larger in width than the opening 136 in the retaining plate 134 while the remainder of the slide member is smaller in width than the opening. The steps 148 contact the retaining plate 134, thereby preventing the slide member 130 from sliding out of the slide bore 126. The part of the slide member 130 that is smaller in width than the opening 136 in the retaining plate 134, however, extends outside of the slide bore 126 and retaining plate 134.

Although a roller type hemming apparatus in accordance with the present invention has been described with reference to more than one embodiment, it should be understood that the features of each embodiment may be interchanged and/or combined.

During the hemming operation, the workpiece W. is placed on the forming surface 20 of the lower die 18, as shown in FIG. 1. The hem roller 16 is pressed with a preset predetermined pressing force against the bent portion of the workpiece W, and a repulsive force of the bent portion causes the robot hand 12 to be deflected in a direction away from the bent portion. The guided slide member 30 is held against the shock absorber 28 by the retaining plate 34 at a predetermined pressure set by the distance between the retaining plate and the support member 24. The hem roller 16 can be maintained on this hemming level, even when the robot hand 12 is deflected within the range limited by the pre-determined pressure applied on the guided slide member 30 in the process described above. If the pressure on the hem roller 16 exerted by the workpiece W exceeds the predetermined pressure, the slide member 30 slides deeper into the slide bore 26 and the excess pressure is absorbed by the shock absorber 28. Thus, the deflection of the robot hand 12 is absorbed and the hem roller 16 is always held on the hemming level, permitting the pressing force of the hem roller 16 to be maintained at a proper value to achieve good hemming.

As described above, as the guided slide member 30 and consequently the hem roller 16 is displaceable with respect to the support member 24 and consequently the robot hand 12, deflection of the robot hand 12, or the difference in the traveling path of the hem roller 16 with respect to the workpiece W, can be absorbed. This permits the hem roller 16 to constantly follow up the bent portion of the workpiece W exactly and to be constantly pressed with a proper pressing force for good hemming.

It is essential to the present invention that the hem roller 16 is displaceable with respect to the robot hand 12, the position of the hem roller 16 being controlled by the position controlling means of the guided slide member 30 and shock absorber 28 assembly. Therefore, the position of the hem roller 16 can be constantly held on the hemming level to achieve good hemming at all times.

Thus, in the hemming apparatus of the present invention, as the hem roller is rotated under a proper pressing force in an accurate traveling path along the peripheral contour of a workpiece, hemming can always be satisfactorily carried out.

Although the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims. 

1. A roller type hemming apparatus comprising: a support member having a slide bore; a compressible fluid shock absorber disposed in said support member, said shock absorber being extendable into said slide bore; a guided slide member received in said slide bore, said slide member contacting said shock absorber; a hem roller; said slide member including a flange disposed outside of said slide bore, said hem roller being rotatably mounted on said flange; and a retaining plate having an opening therein, said retaining plate being mounted to said support member adjacent said slide bore for retaining a portion of said slide member in said slide bore and for limiting travel of said slide member out of said slide bore; whereby the movement of the slide member is tempered during the application of an abrupt compressive force.
 2. The roller type hemming apparatus of claim 1, further including anti-rotate guide members adjacent said retaining plate for limiting rotation of said slide member in said slide bore.
 3. The roller type hemming apparatus of claim 2, where said slide member contacts a surface of said anti-rotate guide members.
 4. The roller type hemming apparatus of claim 1, wherein said slide member has curved sides intermediate a pair of opposed flat surfaces.
 5. The roller type hemming apparatus of claim 4, further including anti-rotate guide members adjacent said retaining plate, said guide members contacting said flat surfaces of said slide member.
 6. The roller type hemming apparatus of claim 1, wherein said slide member has steps such that the portion of said slide member retained in said slide bore is larger in width than the opening in said retaining plate while the remainder of said slide member is smaller in width than said opening.
 7. The roller type hemming apparatus of claim 1, wherein said retaining plate is adjustable to selectively delimit a range of deflection of said slide member, thereby compressing and decompressing said shock absorber to establish a preload force.
 8. The roller type hemming apparatus of claim 7, wherein said retaining plate is adjustable by varying the distance between said retaining plate and said support member.
 9. The roller type hemming apparatus of claim 1, further including a bearing arrangement inserted into said slide bore for guiding said slide member in said slide bore.
 10. The roller type hemming apparatus of claim 1, wherein said apparatus is adapted for operable connection to a work arm of a multi-axis robot.
 11. The roller type hemming apparatus of claim 10, wherein said apparatus is fastened to a forward end of a hand of said robot.
 12. A method of roller hemming, the method comprising the step of: providing a roller type hemming apparatus including: a support member having a slide bore; a compressible fluid shock absorber disposed in said support member, said shock absorber being extendable into said slide bore; a guided slide member received in said slide bore, said slide member contacting said shock absorber; a hem roller; said slide member including a flange disposed outside of said slide bore, said hem roller being rotatably mounted on said flange; and a retaining plate having an opening therein, said retaining plate being mounted to said support member adjacent said slide bore for retaining a portion of said slide member in said slide bore and for limiting travel of said slide member out of said slide bore; whereby the movement of the slide member is tempered during the application of an abrupt compressive force. 